Drill bit



JQ DAHL April 15, 19%..

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V h w Patented Apr. 1.93()l :fUNiTE-o sTnT1= .sl PATENT" oFFlcE l :01m naar., or'- nALLAs, TEXAS, assienon To DAHL BIT conroaarion, or DALLAS,

DRILL :BIT

Application led J'une 1,5,

and it has especial reference to certain new and useful improvements in drill bits of the type wherein a continuous stream of water is injected into the hole being drilled, for proper lubrication of the bit lin operation, and the principal obj ect of the invention resides in the provision in such a bit of .a means to reduce materially the friction created by passage of water and'slush .under pressure through the watercourses in the body of the bit, and to thus increase thelongevity and consequent usefulness of the tool.

The invention has for another object to bring about in such a means as aforesaid, a

considerable reduction in the strain upon the pressure pump employed to circulate water in the hole,.by minimizing friction in the bit, and in so doing, prolonging thelife of the zo pump and increasing its eiliciency.

Still further, the 'invention aims to provide means which are interchangeable and replaceable when samebecome worn by the contact of sand and other cuttingsubstances passing at high velocity which becomes mixed with Water under ump pressure. With the oregoing objects as paramount, the invention has particular- Areference to its salient featuresof construction and arrangement in the'bit, to become manifest as the de l Continuin yscription proceeds, taken in connection with the Vaccompanying drawings, .wherein Figure 1 represents a side elevational view of a bit in which the invention is incorpo-4 rated, parts being brokenaway to better illustrate the same.

Figure 2 isan end, section 011- line Elf-Zot..

Figure 1f. A

Fi re 3 is a :fragmentary view in section of a mo iied example of the invention, an'cl Figure 4 is a detail view of one of the interchangeable bushings. v

now more in detail with the drawings, re erence is primarily made to Fig-` ure 1 in which an improved typeof bit is 1l-" lustrated, the body 1 of which is formed with shoulders 2-'set at such an angle as to allow for rapid circulation of water, and to direct the same upward,'past the shank 3 without interference thereby toretard its progress.

1928.` serial No. 285,521.

This bit is further provided with interchangeable cutting blades 4i, which are' so disposed in the'head as to insure maximum cutting eiiciency.

It will be understood however, that` the specific construction of the. bit shown does not in any way restrict the use of the invention to be presently described in detail, as the invention is adapted for application to any type of earth boring tool employing the circulation of fluid as a lubricating medium.

Accordingly, the invention consists primarily in providing a cavity 5, cored out of the shank 3, which is for the purpose of materially shortening the water coursesi 6, drilled downwardy and outward from the bottom of this cavity to a properpbint for discharging fluidon the operativef'surfaces of the blades- 4. In so shortening the water courses, much friction is obviated 4in passinghazardous condition. lTo so reduce the likelihood of plugging the water courses in the bit is obviously an-important feature in bit construction. f J v Fluidpassingthrough the courses 'often attains a pressure of 1000 pounds and such pressure, if unduly'retarded brings about an enormous strain upon the pump, and when-A possibilities 'of plugging are removed,` normal and efficient performance of the pump is assured, obviously also, adding to the life of thev pump.

Passage of water through the courses 6 at such high velocity, and carrying with it quantities of sand and other similarfsubstances, nally wears upon` the walls of the passages to, such an extent as'to impair the efficiency of the head and it is often necessary to dispense with the tool prematurely. Toobviate Lthis disadvantage and expensive practice, theA f 2 y l 1,754,671

courses 6 are provided with bushings 7 of steel or its equivalent and, as shown in Figure 4, are provided with an annular shoulder 8 about the tops which shoulder prevents the tubular bushing from passing through the passage. These bushings are merely inserted into the passages from the top ends and are not required to be fastened except possibly by making a snug lit. However, in 10 order to aline the lower ends of the bush'- ings, which are obliquely cut to correspond With the exterior surface of the bit stock, a protuberance 9 is formed underneath'the annular shoulder 8 of the bushing, which enters a corresponding recess in the top edge of the passage, as shown in Figures l and 4. With especial reference to Figure 3, a modified showing, instead of providing` a straight cavity as in Figure l, the passages 2g 10 are drilled in the shank 3 at angles with respect to the axis of the body l, and are substantially funnel shaped. In forming the courses thus, even less friction Ais encountered as the fluid does not have to contact with a flat surface, but may pass unrestrictedly through the passages to the outside walls of the body.

In order to remove the bushings 7 from the passages 6, it is required simply toin sert a suitable tool inthe lower end of the passage, and drive the bushing upward.

What is claimed is In a drill bit, a shank having angular bores and bushings in the bores having circular outwardly extendi flan es on their upper ends and having epen ing projections on the under faces of the flanges, the

bushings having their lower ends bevelled to lie flush with the periphery of the Shanks,

` the bores at the upper ends thereof having lateral recesses to receive the projections, the recesses and projections Abeing located and related so that when the pro]ections lie in the recesses the bevelled ends of the bushin are held flush with the shank testimonyI whereof I aixty si nature.

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